Gourmet hamburger chains are spiking milkshakes with everything from beer to red wine in a bid to steal customers from "dry" rivals like McDonald's Corp.

Red Robin Gourmet Burgers Inc on Tuesday will debut a Samuel Adams Octoberfest milkshake, made with vanilla ice cream, beer and caramel, at its roughly 460 restaurants around the country.

Red Robin is not the first restaurant to add booze to milkshakes, which are a menu staple at most burger joints. But its move comes as bartenders take a bigger role in creating menu items that will set more upscale restaurants apart from fast-food chains that often do not sell alcohol.

"Now our guests don't have to choose between a beer or a shake to go with their burger," Donna Ruch, Red Robin's master mixologist in charge of developing alcoholic and nonalcoholic drink recipes, said of the chain's new beer milkshake.

The number of frozen cocktails on restaurant menus is up 52 percent since 2009, despite the flagging popularity of classics like pina coladas, daiquiris and mudslides, according to Mintel Menu Insights, which tracks trends across all types of restaurants.

"Boozy shakes are kind of a thing right now," Mintel food service analyst Kathy Hayden said.

But, as the Red Robin example shows, the combinations don't end with hard alcohol - a traditional ingredient in "adult" milkshakes.

TGI Friday's and a slew of independent restaurants sell milkshakes made with Guinness stout, an Irish dark beer brand, usually around St. Patrick's Day.

The Counter, a Los Angeles-based burger chain, offers a variety of alcoholic shakes, including versions made with red or white wine.

Not to be left behind, fast-food restaurants have been pushing the envelope on nonalcoholic milkshake flavors. For example, fast-food chain Jack In The Box earlier this year caused a stir with its bacon-flavored milkshakes.

Red Robin's beer milkshake is a limited-time offering sold as part of the restaurant's Oktoberfest menu. It will be priced around $5 and served only to patrons of legal drinking age.

The milkshake offers diners a low-cost way to add a little adventure to their meals at a time when the menus at large fast-food burger chains like McDonald's, Burger King and Wendy's have become a "sea of sameness," said Denny Post, Red Robin's chief marketing officer.

"The male at the table is the one more likely to take the bait," Post said.

Mintel's Hayden said a festive, attention-grabbing drink is bound to help differentiate Red Robin from its fast-food rivals. At the same time, the beer shake also should help the company compete with the scores of independent, gourmet burger chains popping up around the country.

While a beer milkshake is a good fit for Red Robin's menu, the jury is still out on whether it will lure new customers - especially the hungry young men who frequent burger chains, Hayden said.

"It will get some curiosity drinkers, but I don't know if it will get new young men in the door," said Hayden, who had not tasted the new milkshake.